Questions: 2. Identify: What fraction of the thickness of the thickest continental crust is the thickness of the oceanic crust? Give your answer as a reduced fraction.

To answer this question, we need to know the typical thicknesses of both continental and oceanic crusts.

1. Typical Thickness of Continental Crust:

   • The continental crust is generally thicker than the oceanic crust. It typically ranges from about 30 km to 70 km. The thickest continental crust is found in mountainous regions, such as the Himalayas, and can be around 70 km thick.

2. Typical Thickness of Oceanic Crust:

   • The oceanic crust is thinner, usually about 5 km to 10 km thick. For this calculation, we will use an average thickness of 7 km for the oceanic crust.

3. Calculate the Fraction:

   • We need to find the fraction of the thickness of the oceanic crust compared to the thickest continental crust.
   • Using the thickest continental crust value of 70 km and the oceanic crust value of 7 km, the fraction is calculated as follows:

   \[ \text{Fraction} = \frac{\text{Thickness of Oceanic Crust}}{\text{Thickness of Thickest Continental Crust}} = \frac{7 \text{ km}}{70 \text{ km}} \]

4. Reduce the Fraction:

   • Simplify the fraction \(\frac{7}{70}\) by dividing both the numerator and the denominator by their greatest common divisor, which is 7:

   \[ \frac{7}{70} = \frac{1}{10} \]

Therefore, the thickness of the oceanic crust is \(\frac{1}{10}\) of the thickness of the thickest continental crust.